The aim of this research is to obtain basic information concerning how the bioenergetic apparatus and reactions in mammalian mitochondria change with the age of golden hamsters on a "common" diet. These data will be rigorously compared with the results obtained under exactly the same conditions except the animal will be rationed with a high-fat diet. The survival curves or mortality rates for these two groups of hamsters will be also recorded with major classification of the causes of the deaths. More specifically, reliable growth charts and accurate mortality rates or survival curves of the hamsters on a "common" diet will be compared with similar data of hamsters on a high-lipid diet which contains an additional 25% saturated fat. At 1.5 to 4 week intervals from new born to the death of all animals, we will study all bioenergetic components and functions. When the focal points due to aging and/or diet are narrowed down or located, we will endeavor an in-depth study to find out "why." At the same time mathematical models simulating the aging process will be pursued. Our premise is that aging can be affected by dietary intake and old age or senescence may be considered a metabolic disease. Rejuvenation may be accomplished clinically and prevented effectively. Our rationale is that in order to achieve this goal to meet increasing demand for older people in the next century because of the changing trends of population growth and socio-economic systems, the cause of so-called senescence must be first uncovered and then remedied.